尚未 is an adverb meaning 'not yet' — it expresses that an expected or anticipated action, state, or event has not occurred up to the present moment. It combines two characters: 尚 (shàng), meaning 'still' or 'yet', and 未 (wèi), meaning 'not' or 'have not'. Together, they form a formal, written-style expression commonly used in news reports, official documents, academic writing, and careful speech. Unlike the more colloquial 还没 (hái méi), 尚未 carries a tone of objectivity and restraint, often implying that the outcome remains pending or uncertain.

This word typically appears before a verb or adjective, modifying the predicate directly — for example, 尚未完成 (has not yet been completed) or 尚未决定 (has not yet been decided). It is rarely used in casual conversation but frequently appears in contexts involving timelines, deadlines, research findings, legal matters, or procedural updates. Its formality makes it unsuitable for informal chats or commands, and it never functions as a standalone sentence element like a noun or verb.